Is it true that humans make only a tiny contribution to the Earth’s carbon cycle each year? Yes. Does this mean that humans aren’t causing global warming? No. Science journalist Graham Wayne explains:

Although our output of 29 gigatons of CO2 is tiny compared to the 750 gigatons moving through the carbon cycle each year, it adds up because the land and ocean cannot absorb all of the extra CO2. About 40% of this additional CO2 is absorbed. The rest remains in the atmosphere, and as a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years (Tripati 2009). (A natural change of 100ppm normally takes 5,000 to 20,000 years. The recent increase of 100ppm has taken just 120 years).

In other words, unlike with the natural carbon cycle, humans add carbon to the atmosphere, but don’t sufficiently offset their carbon footprint with things like, say, planting large tracts of additional forests. The result: a small but steady accumulation of carbon in the atmosphere because of human activity. Nature tends to recycle its carbon, generally maintaining a homeostatic balance, while humans don’t. The slow effect over time is global warming.

5 Responses to Humans Cause Global Warming By Tipping The Balance

Serious question: What is the global temperature ‘supposed’ to be? I get the carbon cycle deal, but the planet has been warming up since the last ice age… steadily. What is the temperature supposed to be? 75 million years ago, I understand, the planet was much warmer than today. What I don’t understand is what the temperature is ‘supposed’ to be. Do you have information on that?

My initial response is that it’s not supposed to be anything, and that it fluctuates over time. The issue is that humans are causing the current natural fluctuation toward warming to accelerate much quicker than it would otherwise. In other words, our behavior changes the climate warming equation from warming a few degrees over, say, 20,000 years, and brings that down to just, say, a hundred years.

I understand this, it seems natural and makes sense. I’ve always held that there are things that we can do which would reduce our carbon footprint, lots of them. I’ve also staunchly held that there are dozens of reasons which are more important than climate for changing what we do.

We can tip the balance back to a cooler planet reasonably quickly by doing a number of things – sadly they all require we act as a collective, one race, one nation. Politics will not only divide us, it will kill us.

Think of homeostasis in medicine. If you are walking, you are warming up compared to sleeping, but your body can handle the processing of your heat by sweating efficiently. But if you start to run, your body may have greater difficulty compensating fully to your rising temperature. Humans are making the planet’s carbon cycle run faster, but it’s not wholly keeping up with the carbon being generated by us. That difference makes for an acceleration in planet temperature. The solution (broadly) is for humans to offset their carbon contribution to the cycle by using energy more efficiently and by, say, planting large tracts of forests, etc.

The carbon footprint concept is something to take seriously (both personally, locally, and globally). It makes for a global ecology ethic that is readily understood and largely correct scientifically.

But, of course, being conscientious about your own carbon footprint and that of your community is akin to voting. Individually, you make no significant difference in making the effort to vote, and yet you still should vote. The synergy of people caring about their carbon footprint (or voting) makes a systemic difference. One person doesn’t matter, and yet we all matter a great deal in aggregate.